Chucks are used to removably secure cutting tools or work-pieces to machining tools, such as metal cutting machines. As is well known in the art, chucks generally have a mounting portion which is adapted to be releasably clamped in the machining tool, and a receiving portion which releasably holds a cutting tool or a work-piece.
U.S. Pat. No. 2,039,149 to Dodge discloses a one way clutch (an over-running, or a free-wheeling clutch) coupling a driving element to a driven element, employing rollers relieved from sliding or rolling loads, having very little back-lash which is further cushioned by an oil film. The over-running clutch comprises inner and outer members, a series of wedge blocks each having on one side a cylindrical surface adapted to be forced into frictional engagement with one of said members, and having a wedge surface on its opposite side, a corresponding series of rollers each arranged between the other of said members and the wedge surface of one of said blocks, and means (i.e., springs) for urging said rollers away from said blocks, said means being independent of said blocks.
When the one way clutch is standing without load, all parts (i.e., the coaxial members, the wedge blocks, the rollers and the springs) are held snugly in engagement. However, when an over-running load is applied, the springs are coiled by the drag of the over running load which works directly against the force of the springs, thereby reversing the load applied by the springs at rest, and reducing the spring load, until a balance of forces is achieved. Additionally, when over-running starts, oil is introduced to form an oil film on the one of said members into which the cylindrical surfaces of the wedge are forced, thereby reducing friction loads. The reverse occurs when driving load is applied, i.e., the pressure on the wedge block increases, urging the oil film out through oil grooves formed on the cylindrical surfaces of the wedge blocks, and the wedge blocks frictionally engage the one of said members.
GB Patent No. 921,522 to Hopkins and Cooper discloses a chuck for holding work-pieces, such as circular section bars. The chuck comprises a generally cylindrical tubular member slitted longitudinally to define at least three fingers. A concentric outer sleeve fits over the cylindrical tubular member. The cylindrical tubular member has an eccentric surface formed on an external finger face of each finger. The outer sleeve has radially inwardly protruding cams on an internal sleeve face thereof. When rotating the sleeve relative to the cylindrical tubular member, the cams of the sleeve slide over the eccentric surface of each finger, urging each finger radially inwardly, and thereby exerting gripping forces on a circular section bar accommodated in the cylindrical tubular member.
U.S. Pat. No. 4,808,049 to Cook discloses a chuck for use on a machine tool. The chuck has a slotted-type collet exhibiting a formed external surface comprising a plurality of exterior cam surface segments disposed circumferentially around the slotted collet. Each of the exterior cam surface segments increases nominally uniformly from a lesser to a greater radius relative to the central axis of the chuck and the slotted collet. The slotted collet cooperates with a tightening sleeve of the tool holder having interior cam surface segments complementary in numbers and in contour to the exterior cam surface segments. Selective rotation of the tightening sleeve relative to the slotted collet causes selective engagement of the complementary interior cam surface segments and the exterior cam surface segments, thereby urging the slotted collet to apply gripping force to a shank of a cutting tool.
U.S. Pat. No. 6,131,916 to Toda discloses a chuck comprising a mounting base and an integral shaft protruding from a center of a front surface of the base and having a tapered surface on the outer peripheral surface thereof. A hole having holding portions and pressure portions which are to be pressurized is formed in the protruding shaft. The holding portions and the pressure portions are alternately arranged, and the holding portions are situated at a plurality of positions equally spaced along an inner periphery of the protruding shaft. Each of the holding portions has a short radius from the center of the hole. The portions to be pressurized are situated between the holding portions and have a long radius from the center of the hole. A rotating cylinder is detachably fitted outside the protruding shaft, and a group of rollers are arranged inside the rotating cylinder so that the axis of the group of rollers is aligned along the axis of the rotating cylinder and supported by an appropriate means. As the rotating cylinder is rotated and moved, the pressure portions are pressed and constricted by the rollers which are in peripheral contact with an outer peripheral surface of the protruding shaft. Thus, the holding portions are expanded (released) in the circumferential direction due to the pressing and constriction of the pressure portions. As a result, an irregular shape of the hole is changed into a perfect circle, facilitating insertion of a proximal portion of a tool into the now perfectly-circular hole. Following insertion of the proximal portion of the tool into the chuck, the rotating cylinder is rotated and moved from the long diameter portion to the short diameter portion of the tapered surface of the protruding shaft. Consequently, the group of rollers stops pressurizing the pressure portions. Thus, the holding portions are not expanded. The proximal portion of the tool in the hole is held by the holding portions, which are now restored to the original shape. When the tool is held in the chuck, the rotating cylinder is removed from the protruding shaft. To remove the tool from the protruding shaft, the rotating cylinder is used again to press and constrict the pressure portion in order to expand the holding portions in the circumferential direction. As a result, the irregular shape of the hole in the clamping position is restored into the perfect circle of the released position, facilitating removal of the proximal portion of the tool from the now perfectly-circular hole.
It is an object of the present disclosure to provide an improved chuck. This object is attained with the subject matter in accordance with the claims.